#807: r.watershed doesnt consider longer distance to diagonal neighbouring pixels ---------------------+------------------------------------------------------ Reporter: aread | Owner: [email protected] Type: defect | Status: new Priority: major | Milestone: 6.4.0 Component: Raster | Version: 6.4.0 RCs Resolution: | Keywords: r.watershed Platform: All | Cpu: All ---------------------+------------------------------------------------------ Comment (by helena):
I finally had chance to look at it and it does make a significant difference (much more than I would have ever guessed) and I think that after some more testing the fix should go to the GRASS64 release as a bugfix. Some examples from the nc_spm_08 data set 1m resolution old http://skagit.meas.ncsu.edu/~helena/wrriwork/lakewh/flowD8dem.jpg new http://skagit.meas.ncsu.edu/~helena/grasswork/accum_5Kdiagfix.png red is the stream from high res ortho http://skagit.meas.ncsu.edu/~helena/grasswork/accum_5Kdiagfix2.png.png I haven't done any serious testing but brief visual comparison indicates that the fix may improve the accuracy of stream extraction beyond just looking more realistic) red-sreams from ortho, blue-old, black-new http://skagit.meas.ncsu.edu/~helena/grasswork/accum_diagfix_streams.png example with the 30m ned shows quite a few differences - see the first stream from the west on these two images with the fix apparently better although still with some error: http://skagit.meas.ncsu.edu/~helena/grasswork/accum_10Korig.png http://skagit.meas.ncsu.edu/~helena/grasswork/accum_10kfix.png It would be very useful if anybody who has some other data than nc_spm and some orthos to compare the results with runs another test and confirms that the change can go into 64, Markus, thanks for fixing it so quickly, Helena -- Ticket URL: <https://trac.osgeo.org/grass/ticket/807#comment:3> GRASS GIS <http://grass.osgeo.org>
_______________________________________________ grass-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-dev
